Industry produces solid containing wastes, such as refinery sludge, solids-stabilized emulsions, contaminated soils and the like that require disposal. Some of these wastes are listed as hazardous wastes by the Environmental Protection Agency (EPA) and are regulated under legislation such as the Resource, Conservation, and Recovery Act (RCRA). The term hazardous waste is defined by relevant government rules and regulations, in particular RCRA, and further refers to organic and/or inorganic material or combinations of organic materials which are "listed" by the Environmental Protection Agency as hazardous, or which exhibit ignitability, corrosively or reactivity. The term solid waste refers to any garbage, sludge or other waste material. In the past, solid wastes such as refinery sludge have been disposed of by land fills and land farms. To comply with current regulations, the constituents of the solid waste must be treated to separate some of the organic materials, to destroy cyanides and to fixate metals.
It is desirable to extract the organics, destroy the cyanide, fixate the metals and remove the water from the solids prior to disposal in approved land fills. Further, it is desirable to recycle valuable components of the solid waste prior to disposal. Alternatives to conventional land fills are being examined in view of environmental concerns and considerations.
Various technologies for treating wastes to render the solids acceptable for land disposal are being developed and have been examined, but none has been found entirely satisfactory. Solvent extraction processes for treating wastes are mostly in the developmental stage. Limitations to solvent extraction technologies are consistency of treatment performance, toxicity of spent solvents and a non-integrated system for waste treatment. Other methods to process wastes include incineration and vitrification. Incineration is energy intensive, and not a publicly acceptable method of disposal. Vitrification is a thermal treatment process that converts contaminated soil into a chemically inert and stable product by means of high heat, and is also highly energy intensive.
We have discovered a water-managed solvent extraction process that treats solid waste efficiently, economically and reliably resulting in products acceptable for land disposal. We have found a process that deliberately controls the water throughout the process by capturing the water at the beginning of the process and releasing it at the end as recovered water. The organic removal from the waste is more thorough, reliable and predictable by managing the water in the process. It will become evident that the process of the instant invention is an integrated system that treats solid organic waste by extraction of the organics, destruction of the cyanides and fixation of metals while focusing on a directed distribution, transfer and mass balance of water throughout the overall process. Further, it will be seen that the process of the instant invention can produce recyclable and/or sellable end products, thus contributing to the overall environmental and societal concerns of the 1990's and beyond.
It is the object of the instant invention to provide a water-managed solvent extraction process that treats solid wastes.
It is another object of the instant invention to provide a solvent extraction process that controls water distribution during solid waste treatment.
It is another object of the instant invention to provide a method for the dehydration of waste and the solubilization of organic materials, fixation of metals, and destruction of cyanide to produce a treated product that is acceptable for land disposal.
These and other objects together with the advantages over known methods shall become apparent from the specification which follows and are accomplished by the invention herein described and claimed.